This application claims the priority of Italian patent application Serial No. GE2000 A 14 filed on Feb. 4, 2000.
The present invention relates to a method for the production of a purified sacchariferous juice from raw juices obtained from sacchariferous material of vegetable origin, and in particular from sacchariferous plants such as sugar beet or sugar cane.
Typically, in the purification, on an industrial scale, of raw sugar-beet juices, huge quantities of lime are used and therefore in these production plants furnaces for producing the lime from limestone are required. The clear juices obtained following this treatment, which is generally performed twice during the course of the same purification process, are then concentrated and crystallised in order to produce the sugar.
This type of technology, which has been used for a very long time in the sector, has high costs from an energy point of view, in addition to a considerable environmental impact due essentially to the clarification sludges of the juices, which may constitute as much as 8-10% of the beet treated. Moreover, it must also be stated that this method requires the use of a considerable quantity of quarry lime, in the region of 5% and more, relative to the weight of the beet.
Methods for purification of the raw juices which do not involve the use of lime treatment are known; in particular, these methods make use of filtration onto suitable membranes. These systems, however, have encountered objective difficulties with regard to their industrial application, since the suspended substances present in the raw juices cause blockage of the membranes and the stagnation thereof forms areas which are the source of infection.
The object of the present invention is therefore to provide a method for the preparation of a purified sugary juice which, not involving purification operations which use lime treatment, may be both readily and effectively applied on an industrial level.
The present invention therefore relates to a method for the preparation of a purified sugary juice from raw juices obtained from sacchariferous material of vegetable origin, comprising the steps of:
coarse filtration of the extracted juice by means of diffusion and/or pressing of the vegetable mass;
correction, if necessary, of the pH and subsequent heating of the previously filtered juice;
addition of a suitable processing adjuvant, for example a; coagulating agent, to the juice, preferably with stirring;
separation of the juice from the suspended phases; and
membrane-filtration of the juice thus obtained.
In a mode of implementation of the method according to the present invention, coarse filtration is performed by means of a steel-mesh filter with openings in the range of 200-1000 xcexcm, preferably in the region of 500 xcexcm.
Heating, where necessary, is performed to a temperature generally of between 75 and 95xc2x0 C., and preferably 80 and 85xc2x0 C.
The processing adjuvant which is introduced into the raw juice is preferably a polycationic polymer coagulating agent, such as in particular poly-diallyl-dimethylammonium chloride.
Further advantages and characteristic features will emerge from the following description of a mode of implementation of the method according to the present invention, provided, by way of a non-limiting example, with reference to the sole accompanying plate of drawings, in which: